Method for evaluating equivalent conversion of cement paste dispersion resistance

Abstract

The application discloses a cement paste anti-dispersion performance equivalent conversion evaluation method, which comprises the following steps: adopting a rotating center principle to design an experiment, ensuring cement paste compatibility randomness; preparing cement paste, and performing anti-dispersion performance test on fresh cement paste; simultaneously measuring cement loss and suspended matter content in a suspension liquid by using a weighing method, and measuring the turbidity of the suspension liquid by using a turbidimeter; analyzing the cement loss and the suspended matter content of the cement under water under different compatibilities, establishing an underwater anti-dispersion performance model of the cement paste system, analyzing the turbidity of the cement suspension liquid, and establishing a suspension liquid turbidity model of the cement paste system; establishing an underwater anti-dispersion performance and suspension liquid turbidity equivalent conversion relationship of the cement paste system; and evaluating the underwater anti-dispersion performance of the cement paste through the suspension liquid turbidity of the cement paste. The application has the following advantages: test speed is greatly improved, the test process is efficient and accurate, the test process is simple to operate, and the test process has good repeatability.

Description

Technical Field

[0001] This invention belongs to the technical fields of water conservancy engineering and materials engineering, and specifically relates to an equivalent conversion evaluation method for the anti-dispersion performance of cement paste. Background Technology

[0002] Cement slurry is widely used in underwater operations, such as tunnels and underwater rockfill dams, in fields such as water conservancy and materials engineering. However, due to the complexity of the underwater environment, the anti-dispersion performance of cement slurry is greatly challenged, and dispersion is prone to occur, causing great inconvenience and safety hazards to underwater operations.

[0003] Traditional methods for measuring the underwater anti-dispersion properties of cement slurry require weighing and subsequent processes such as filtration, evaporation, and sedimentation of the suspension, resulting in significant waste of manpower, resources, and time. To provide technical support for the safety and reliability of underwater engineering, ensure the smooth operation of underwater tasks, and promote the application and adoption of cement in underwater environments, it is necessary to optimize and improve the testing methods. These methods should be easy to operate, provide reliable data, have short testing cycles, and effectively evaluate the underwater anti-dispersion properties of cement slurry to meet the needs of practical field applications.

[0004] In the field of aquatic ecology and water environment, turbidimeters are commonly used to characterize various features of suspensions. Turbidimeters have a simple working principle and the testing process is simple and efficient. However, to date, there are no relevant cases of using turbidimeters to measure the turbidity of cement slurry suspensions to evaluate the underwater anti-dispersion performance of cement. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention provides an equivalent conversion evaluation method for the anti-dispersion performance of cement paste.

[0006] This invention adopts the following technical solution: a method for evaluating the equivalent conversion of the anti-dispersion performance of cement paste, comprising the following steps:

[0007] Step 1: Prepare cement slurry according to the compatibility criteria. During the preparation process, ensure that the mineral admixture and cement particles are uniformly mixed and that the mineral admixture fully coats the cement particles, so that the cement slurry can fully exert its underwater anti-dispersion properties; then perform dispersibility testing on the cement slurry.

[0008] Step 2: Separate the suspended solids in the cement paste, and use the weighing method to measure the amount of cement loss and the content of suspended solids in the cement paste; use a turbidimeter to measure the turbidity of the suspension to obtain the turbidity value;

[0009] Step 3: Using the cement loss and suspended solids content from Step 2 as response values, establish an underwater anti-dispersion model for cement paste using response surface methodology; using the turbidity value from Step 2 as the response value, establish a turbidity model for the suspension of cement paste using response surface methodology.

[0010] Step 4: Fit the underwater anti-dispersion performance model of cement paste with the turbidity model of suspension to obtain the suspended solids content Y. SQ and response turbidity Y T Derive and establish the equivalent conversion relationship between the underwater anti-dispersion performance of cement paste system and the turbidity of suspension;

[0011] Step 5: Based on the statistical results of Step 2 and Step 4, analyze the comparative relationship between the underwater cement loss, suspended solids content, and turbidity of the cement slurry and its underwater anti-dispersion performance.

[0012] Based on the turbidity assessment of the cement slurry suspension with different cement slurry formulations in step one, the underwater anti-dispersion performance of cement slurry with different formulations is predicted.

[0013] In a further embodiment, the cement paste includes at least the following components: silicate cement, underwater non-dispersant, and mineral admixtures.

[0014] In a further embodiment, the underwater anti-dispersion model of the cement paste in step three is expressed in the following form:

[0015]

[0016] In the formula, Y SQ A represents the suspended solids content, B represents the underwater non-dispersant content, and C represents the mineral additive content. SQ α is the coefficient of the constant term. SQ β SQ All are coefficients of the linear term, τ SQ , and σ SQ All are coefficients of quadratic terms.

[0017] In a further embodiment, the turbidity model of the cement paste suspension in step three is expressed by the following formula:

[0018]

[0019] In the formula, Y T In response to turbidity, A represents the content of underwater non-dispersant, B represents the content of mineral admixtures; C T α is the coefficient of the constant term. T β T All are coefficients of the linear term, τ T , and σ T All are coefficients of quadratic terms.

[0020] In a further embodiment, the equivalent conversion relationship between the underwater anti-dispersion performance and the turbidity of the suspension is satisfied by the following formula:

[0021] Y T =C+εY SQ In the formula, C is the coefficient of the constant term, and ε is the coefficient of the linear term.

[0022] In a further embodiment, the suspended matter is separated by at least one of filtration, evaporation, and precipitation.

[0023] In a further embodiment, the sample volume when measuring and calculating the cement loss and suspended matter content of cement paste using the weighing method is defined as V1, and the sample volume when measuring the turbidity of the suspension and calculating the turbidity value using a turbidimeter is defined as V2, wherein V1 and V2 satisfy the following relationship: V1 = V2.

[0024] In a further embodiment, the relevant terms remain consistent when creating the underwater anti-dispersion model and the suspension turbidity model.

[0025] In a further embodiment, when creating the underwater anti-dispersion model and the suspension turbidity model, a 95% confidence space and prediction space are retained.

[0026] The beneficial effects of this invention are: significantly improved testing speed: compared with traditional measurement methods such as weighing and filtration, the turbidity value can be obtained immediately by simply injecting the suspension to be tested into the instrument. The whole testing process is very fast, saving time and effort.

[0027] The testing process is highly efficient and accurate: Traditional methods introduce operational errors during filtration, drying, and weighing, and these errors are unavoidable for laboratory personnel. In contrast, a turbidimeter measures the scattering and absorption characteristics of particles in a suspension, quickly and accurately reflecting the concentration and size distribution of particles, thus directly indicating the anti-dispersion performance of the cement paste.

[0028] The testing process is simple to operate: using a turbidimeter, you only need to inject the suspension to be tested into the instrument and press the start button to automatically measure. There is no need for cumbersome sample preparation, weighing and other operations, which is very simple and easy to do.

[0029] The test process has good repeatability: the turbidimeter has high repeatability and stability, and can be repeatedly tested under different experimental conditions to obtain stable and reliable test results. Attached Figure Description

[0030] Figure 1This is a flowchart of an equivalent conversion evaluation method for the anti-dispersion performance of cement paste according to the present invention.

[0031] Figure 2 This invention employs a weighing method to measure the underwater anti-dispersion performance response model of cement.

[0032] Figure 3 This invention employs a turbidimeter to measure the turbidity response model of cement suspension.

[0033] Figure 4 This invention provides an equivalent conversion model for the response values ​​of underwater anti-dispersion performance and cement suspension. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0035] like Figure 1 As shown, a method for evaluating the equivalent conversion of the anti-dispersion properties of cement paste includes the following steps:

[0036] Step 1: Prepare cement paste according to the compatibility criteria. During the preparation process, ensure that the mineral admixture and cement particles are uniformly mixed, and that the mineral admixture fully coats the cement particles, allowing the cement paste to fully exert its underwater anti-dispersion performance. Perform dispersibility testing on the cement paste. In this embodiment, the cement paste includes at least the following components: silicate cement, underwater anti-dispersion agent, and mineral admixture. The silicate cement used is ordinary silicate cement with a strength grade of 42.5 or higher. The underwater anti-dispersion agent is a flocculant with cationic polyacrylamide as its main component. The mineral admixture is ultrafine powder. The underwater anti-dispersion agent and mineral admixture are used as variables to regulate the underwater anti-dispersion performance of the cement paste. The experiment is designed using the center of rotation principle to ensure the randomness of the cement paste compatibility.

[0037] In other words, according to the compatibility of the cement paste preparation, it is necessary to ensure that the mineral admixtures and cement particles are uniformly mixed during the preparation process, and that the admixture mixture fully coats the cement particles so that the cement paste can give full play to its underwater anti-dispersion performance. Anti-dispersion performance tests are then conducted on the freshly mixed cement paste.

[0038] Step 2: Separate the suspended solids in the cement slurry, and use the weighing method to measure the amount of cement loss and the content of suspended solids in the cement slurry; use a turbidimeter to measure the turbidity of the suspension to obtain the turbidity value.

[0039] In a further embodiment, the suspended solids are separated from the sample per unit volume through methods such as filtration, evaporation, and precipitation. The content of the suspended solids can be obtained by weighing the mass of the suspended solids. At the same time, the turbidity of the suspension is measured using a turbidimeter. When measuring the turbidity of the suspension, the intensity of scattered light in the suspension is measured by the turbidimeter, and the turbidity value is calculated based on optical principles.

[0040] The sample volume is defined as V1 when the cement loss and suspended solids content of cement paste are measured and calculated by weighing method, and the sample volume is defined as V2 when the turbidity of the suspension is measured and calculated by turbidity meter. In order to ensure that the turbidity of the suspension can effectively reflect the suspended solids content under this condition and reduce the uncertainty caused by experimental factors, V1 and V2 should satisfy the following relationship: V1 = V2.

[0041] Furthermore, when using a turbidimeter to measure the turbidity of a suspension and calculate the turbidity value, the surface of the sampling bottle must be wiped clean to prevent it from affecting the test results.

[0042] Step 3: Using the cement loss and suspended solids content from Step 2 as response values, establish an underwater anti-dispersion model for cement paste using response surface methodology; using the turbidity value from Step 2 as the response value, establish a turbidity model for the suspension of cement paste using response surface methodology.

[0043] It should be noted that the relevant terms remain consistent when creating the underwater anti-dispersion model and the suspension turbidity model. A 95% confidence space and prediction space are also retained to determine equivalence relationships.

[0044] In a further embodiment, the underwater anti-dispersion model of the cement paste in step three is expressed using the following response mode:

[0045]

[0046] In the formula, Y SQ A represents the suspended solids content, B represents the underwater non-dispersant content, and C represents the mineral additive content. SQ α is the coefficient of the constant term. SQ β SQ All are coefficients of the linear term, τ sQ , and σ SQ All are coefficients of quadratic terms.

[0047] In other words, the underwater anti-dispersibility model shows that the suspended solids content of cement is related to the content of underwater non-dispersant and mineral admixture, exhibiting a quadratic function relationship. Furthermore, there is an interaction between the underwater non-dispersant and mineral admixture, affecting the suspended solids content of the cement paste.

[0048] The underwater anti-dispersion model was validated: the traditional weighing method showed that the underwater anti-dispersion performance of cement paste was significantly related to the suspended solids content. If the underwater anti-dispersion performance of cement paste was judged to be excellent when the cement dispersion content did not exceed 1.5%, the model showed that the compatibility of the mixture with a suspended solids content not exceeding 250 mg / L met the condition.

[0049] In a further embodiment, the turbidity model of the cement paste suspension in step three is expressed in the following manner: In the formula, Y T In response to turbidity, A represents the content of underwater non-dispersant, B represents the content of mineral admixtures; C T α is the coefficient of the constant term. T β T All are coefficients of the linear term, τ T , and σ T All are coefficients of quadratic terms.

[0050] In other words, the suspension turbidity model in this embodiment reflects that the turbidity of cement suspension is related to both the content of underwater non-dispersant and the content of mineral admixtures, exhibiting a quadratic function relationship. Furthermore, there is an interaction between the underwater non-dispersant and the mineral admixtures, which affects the turbidity of the cement paste suspension.

[0051] The turbidity model of the suspension was validated: Turbidity meter measurement showed that the underwater anti-dispersion performance of cement paste was significantly correlated with the turbidity of the suspension. If the underwater anti-dispersion performance of cement paste is judged to be excellent when the cement dispersion content does not exceed 1.5%, the model shows that the compatibility of the suspension with a turbidity not exceeding 400 NTU meets the condition.

[0052] Step 4: Fit the underwater anti-dispersion performance model of cement paste with the turbidity model of suspension to obtain the suspended solids content Y. SQ and response turbidity Y T Derive and establish the equivalent conversion relationship between the underwater anti-dispersion performance of cement paste system and the turbidity of suspension;

[0053] Based on the turbidity assessment of the cement slurry suspension with different cement slurry formulations in step one, the underwater anti-dispersion performance of cement slurry with different formulations is predicted.

[0054] In a further embodiment, the equivalent conversion relationship between underwater anti-dispersion performance and suspension turbidity is satisfied by the following formula:

[0055] Y T =C+εY SQ In the formula, C is the coefficient of the constant term, and ε is the coefficient of the linear term.

[0056] The suspended solids content of cement paste is linearly correlated with the turbidity of the suspension. Therefore, it is reasonable and well-founded to assess the underwater anti-dispersion performance of cement by using the turbidity of the suspension.

[0057] The following thirteen examples further illustrate this point. As shown in Table 1, thirteen sets of cement pastes with different proportions were randomly generated based on the compatibility. Step two was used to calculate the suspended solids content and turbidity value of the thirteen examples. The obtained suspended solids content and turbidity value were used as response values. Fitting terms were selected, ensuring that the fitting terms were significant while the model lack of fit terms were not significant to prove the feasibility of the response model. Model R 2 A value greater than 0.9 indicates excellent fitting performance. Finally, the estimated coefficients of each fitting term are obtained to establish an underwater anti-dispersion model for cement paste, such as... Figure 2 As shown, the response model is:

[0058] Y SQ =77-164.45A-150.55B+68.00AB+83.81A 2 +148.56B 2 .

[0059] Using the concentration of the cement slurry suspension as the response value, a turbidity model for the cement slurry suspension is similarly established using the response surface methodology. It should be noted that the selected fitting terms must be consistent with those selected in the underwater anti-dispersion model of the cement slurry to ensure that the suspended matter and turbidity in the suspension are consistent with the influencing factors. Figure 3 As shown, the response model is represented as follows:

[0060] Y T =180.20-139.52A-99.30B-9.75AB+99.09A 2 +142.59B 2 .

[0061] The fitting equations for the underwater anti-dispersion performance model and the turbidity model of the cement slurry system were derived, and an equivalent conversion model between the underwater anti-dispersion performance and the turbidity of the cement slurry system was established, as follows: Figure 4 The equivalent equation is:

[0062] Y T =152.51+0.80Y SQ .

[0063] Table 1 Evaluation of the underwater anti-dispersion performance of cement paste

[0064]

[0065] Note: In the table, A indicates excellent anti-dispersion performance, B indicates average underwater anti-dispersion performance, and C indicates extremely poor underwater anti-dispersion performance.

Claims

1. A method for evaluating the equivalent conversion of the dispersion resistance of a cement paste, characterized by, The method comprises the following steps: Step one, mixing to prepare the cement paste, ensuring uniform mixing of the mineral admixture and cement particles during the preparation process, and fully wrapping the cement particles with the mineral admixture to fully exert the underwater dispersion resistance of the cement paste; testing the underwater dispersion resistance of the cement paste; Step two, separating the suspended matter in the cement paste, measuring the cement loss and suspended matter content of the cement paste by weighing method; measuring the turbidity value of the suspended liquid by turbidimeter; Step three, using the cement loss and suspended matter content in step two as the response value, and establishing an underwater dispersion resistance model of the cement paste by response surface method; using the turbidity value in step two as the response value, and establishing a suspended liquid turbidity model of the cement paste by response surface method; Step four, fitting the model of underwater dispersion resistance of cement paste with the model of suspension content of turbidity of suspension and response turbidity is derived, establishing the equivalent conversion relationship between the underwater dispersion resistance of cement paste system and the turbidity of suspension. Step five, combining the results of step two and step four, analyzing the comparative relationship between the underwater cement loss, suspended matter content and suspended liquid turbidity of the cement paste and the underwater dispersion resistance of the cement paste; Based on the evaluation of the suspended liquid turbidity of the cement paste in step one, the underwater dispersion resistance of the cement paste under different combinations is predicted.

2. The method for evaluating the dispersion resistance performance of cement paste according to claim 1, characterized in that, The cement paste comprises at least the following components: Portland cement, underwater non-dispersing agent and mineral admixture.

3. The method for evaluating the dispersion resistance performance of cement paste according to claim 1, characterized in that, The underwater dispersion resistance model of the cement paste in step three is expressed by the following response mode: ； In the formula, is the content of the suspending agent, A is the content of the water non-dispersing agent, and B is the content of the mineral additive; is a constant term coefficient, , are linear term coefficients, , and are quadratic term coefficients.

4. The method for evaluating the dispersion resistance performance of cement paste according to claim 1, wherein, The suspended liquid turbidity model of the cement paste in step three is expressed by the following mode: ； In the formula, A is the content of the underwater non-dispersant, B is the content of the mineral additive, is a constant term coefficient, , are linear term coefficients, , and are quadratic term coefficients.

5. The method for evaluating the dispersion resistance performance of cement paste equivalent conversion according to claim 1, characterized in that, The equivalent conversion relationship between the underwater dispersion resistance and the suspended liquid turbidity satisfies the following formula: ; where, is a constant term coefficient, is a linear term coefficient.

6. The method for evaluating the dispersion resistance performance of a cement paste according to claim 1, wherein At least one of the following methods is used to separate the suspended matter: filtration, evaporation and precipitation.

7. The method for evaluating the dispersion resistance performance of cement paste equivalent conversion according to claim 1, characterized in that, The sample volume for calculating the cement loss and the suspended matter content of the cement paste by the gravimetric method is defined as The sample volume for calculating the turbidity value by measuring the turbidity of the suspension with a turbidimeter is wherein and satisfy the following relationship: .

8. The method for evaluating the dispersion resistance performance of a cement paste according to claim 1, characterized by, When creating the underwater dispersion resistance model and the suspended liquid turbidity model, the related items remain consistent.

9. The method of evaluating the dispersion resistance performance of a cement paste according to claim 1, wherein, When creating the underwater dispersion resistance model and the suspended liquid turbidity model, the significance is verified by variance analysis, and the confidence interval and prediction interval with 95% confidence are calculated.

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